A growing number of states are supporting renewable electricity through the creation of renewable portfolio standards (RPSs), according to a report released by Lawrence Berkeley National Laboratory. "Renewables Portfolio Standards in the United States: A Status Report with Data through 2007" provides a comprehensive overview of early experience with these state-level RPS policies.

"State RPS policies require utilities to buy a certain amount of renewable energy, and these programs have emerged as one of the most important drivers of renewable energy deployment in the U.S," notes report author Ryan Wiser of Berkeley Lab. "But, as the popularity and importance of these RPS' has increased, so, too, has the need to keep up with the design, early experience and projected impacts of these programs."

Collectively, the RPS policies that are in place today in 25 states and Washington, D.C., apply to nearly 50% of U.S. electricity load, and four new states joined the RPS roster in 2007. Some of the key findings of the study include:

- over 50% of non-hydro renewable capacity additions in the U.S. from 1998 through 2007 occurred in states with RPS policies, and 93% of these additions came from wind power;

- existing state RPS policies, if fully achieved, would require roughly 60 GW of new renewable capacity by 2025, equivalent to 15% of projected electricity demand growth from 2000 through 2025;

- renewable energy certificate (REC) tracking systems continue to expand, and all but four states allow unbundled RECs to count towards RPS compliance; and

- the cost of RPS policies varies by state, but in most states, these programs have, so far, increased electricity rates by 1% or less; in several states, the renewable electricity required by RPS policies appears competitive with fossil generation.